US 3520627 A
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YASUHARU SUZUKI WRITING INSTRUMENT Filed Aug. 12, 1968 INVENTOR SUKLL ATTORNEY United States Patent 3,520,627 WRITING INSTRUMENT Yasuharu Suzuki, Yokohama, Japan, ssignor to Mitsubishi Pencil Company Limited, Tokyo, Japan Filed Aug. 12, 1968, Ser. No. 751,851 Int. Cl. B431: 19/14 US. Cl. 401-96 2 Claims ABSTRACT OF THE DISCLOSURE A Writing instrument, such as a pencil which may be sharpened, has a coating on the shaft part of a heat shrinkable synthetic resin to prevent damage.
This invention relates to a writing instrument.
Wooden shafts of a pencil or ball pen are generally painted with a lacquer to prevent staining and to improve appearance. However, ten or more painting steps are usually required for such painting, making the production very complicated and increasing the manufacturing cost. Further, paints and solvents are inflammable and are, therefore, dangerous to handle. Further, a film of the paint is not strong. Consequently, for a pencil which is to be sharpened with a pencil-sharpener, the shaft may be damaged by the pawls in the clutching part.
Therefore, an object of the present invention is to provide a writing instrument which eliminates several painting steps in manufacture, and which has a protected wooden shaft.
In the accompanying drawings:
FIG. 1 is an elevation view, partly in section, of a writing tool embodying the present invention;
FIG. 2 is an enlarged end view of FIG. 1;
FIG. 3 is an enlarged view of a part of FIG. 1.
Each of FIGS. 4 and 5 is an elevation view, partly in section, showing assembly of a writing instrument embodying the present invention.
The drawings show an embodiment of the present invention comprising a pencil. As shown in FIGS. 1 to 3, a black or colored lead 1 is fitted in the center of a hexagonal pillar-shaped wooden shaft 2, which is provided on the outside surface with a film 4 of such heat shrinkable synthetic resin as polyvinyl chloride, vinyl chloride or polypropylene. An adhesive layer 3, which softens when heated, such as a vinyl acetate or butadiene acrylenitril rubber or similar material, is used. The adhesive layer 3 prevents the film 4 from being peeled off when the wooden shaft of the pencil is sharpened. Further, an eraser 5 arranged at one end of the wooden shaft 2 is held by an extension of the film 4.
In making such a pencil, the wooden shaft 2 fitted in the center with the lead 1 is made by a conventional process and is painted, as required, with the adhesive layer 3 described above. In applying this adhesive, any conventional pencil painting apparatus can be utilized. For example, paint tub is filled with the adhesive and is heated to a suitable temperature, i.e. 140 C.-150 C., to keep the adhesive molten. One or two coats of the adhesive is sufficient.
As shown in FIG. 4, the wooden shaft 2 is inserted through a tube 411 of heat shrinkable synthetic resin having a diameter several tens of percent larger than the diameter of the pencil. The eraser 5 is arranged at one end. When the assembly is, then, passed through a heating furnace or has hot air blown on it so that the tube 4a may be heated to to C., said tube will shrink and, therefore, the film 4 of the heat shrinkable synthetic resin closely adheres to the outside of the wooden shaft, as shown in FIG. 5.
Further, the adhesive layer 3 has been softened by the above mentioned heating, so that when it is cooled, the film 4 will be bound and fixed to the wooden shaft 2. Thus, when the pencil is sharpened, the film at the sharp ened end is prevented from peeling off. If any patterns or letters are printed in advance on the tube 4a of the heat shrinkable synthetic resin, they can be shown on the outside surface of the completed pencil. Needless to say, it is also possible to print or stamp the surface after the film 4a is formed. Also, any desired coloring or letter printing may be applied to the wooden shaft before the film 4 is formed and, then, a transparent heat shrinkable synthetic resin film 4 may be formed on the outside. The pencil on which the film 4 is thus formed has the end part cut off to be completed as shown in FIGS. 1 to 3.
As described above, the writing instrument of the present invention has a film of a heat shrinkable synthetic resin formed on the outside surface of the shaft. This eliminates inflammable paint in the manufacturing process. Therefore, the pencil can be more safely made and sanitation in the factory can be improved. Further, the coating can be applied simply and efficiently. The film is not likely to change in color and quality with the lapse of time. In case of a pencil, the wooden shaft can be easily sharpened and the eraser can be very simply fitted. Further, the film is so strong and elastic that it is not hurt even if the pencil is clutched with the pawls of a pencil sharpener.
What is claimed is:
1. A writing instrument comprising a writing element, a sheath fixedly adhered throughout its length to and enclosing said writing element, which sheath is sharpenable to expose the element for writing, an eraser adjacent one end of said sheath and a heat shrunken film of synthetic resin formed on the outer surface of said sheath and said eraser.
2. The writing instrument of claim 1 including an adhesive layer disposed between said film and said sheath for binding the former to the latter.
References Cited UNITED STATES PATENTS 2,390,473 12/1945 Teichner 401-96 2,790,285 4/1957 Pike et a1 156-86 3,113,482 12/1963 Hirsch 156-86 FOREIGN PATENTS 220,914 4/1959 Australia.
LAWRENCE CHARLES, Primary Examiner